SURFACE AND DEEP TOW-NETTING. 15? 



as an attractive influence, in others as a repellant ; and it 

 is not improbable, as evidence seems to favour, that dif- 

 ferent intensities or kinds of light, whether as sunlight, 

 moonlight, or electric light, have various degrees of 

 attractive or repelling power. 



At a depth of 33 fathoms, when about six miles west of 

 Peel, a cast of the steamer's large trawl was made, a finely- 

 meshed tow-net being fixed to the line at about 3 fathoms 

 distance from the trawl. As the vessel slowly proceeded 

 the tow-net would be within a varying few feet from the 

 sea bottom. Simultaneously a similar tow-net was let 

 out at the stern of the ship, and allowed to run at the 

 surface and to within a few feet thereof. 



The temperature of the surface water was about 44° 

 Fahr., and only a slight ripple on the sea, and a cloudy 

 sky without sunshine. 



Experience has often annoyingly shown us the great 

 risk to which a bottom tow-net, attached to a trawl or 

 dredge, is exposed from its passing over rough ground, 

 the tow-net frequently being either bodily carried away 

 or torn in such a way that the entire contents have 

 escaped. It was, therefore, with much satisfaction that 

 on this occasion when the trawl was hauled up after 1J 

 hours immersion, the vessel steaming very slowly mean- 

 time, although the trawl-net itself was torn, the tow-net 

 was found to be in perfect condition, and containing a 

 considerable quantity of living plankton. 



At the same moment the surface net was taken in, and 

 the contents of each net were immediately preserved in 

 bottles containing a 5 % solution of Formol and sea- water. 



The following table is a summary of the respective 

 contents, Copepoda forming, as might be expected, by far 

 the largest proportion of each. 



Allowing the contents time to sink the amount of 



